The use of inertial torsional damping devices to minimize torsional vibrations in rotating shafts is well known, particularly in motor vehicle drivetrain rotating shafts. Typically, torsional dampers are a separate component attached to a vehicle's rotating shaft. It is known to either press-on or bolt the torsional damper to the shaft.
One known system is disclosed in U.S. Pat. No. 5,168,774 (Andrä et al.) Andrä{umlaut over ( )} et al. teach a rotational body made of a deep-drawn sheet metal portion having an integral hollow cylindrical center portion. The body also includes a metallic shrink-on sleeve immovably affixed to the outer circumference of the center portion.
There are several disadvantages to this system. One disadvantage is that the rotational body is an additional component that must be added to the rotating shaft. In other words, it serves no purpose other than a vibrational damping device. Therefore, it requires additional assembly and takes up additional space along the driveline of the vehicle.
Another known system is disclosed in U.S. Pat. No. 4,884,666 (Stahl.) Stahl teaches a torsional damper for mounting between a first shaft and a second shaft. The housing of the torsional damper has a ring shaped sealed cavity and an annular inertia weight rotatably mounted in the cavity in an unattached, concentric and slidable relationship with the housing cavity. A clearance exists between the inertia weight and the housing completely surrounding the inertia weight. Either a viscous fluid or a type of bearing may occupy the clearance. The clearance functions as a medium to dampen torsional vibration and noise. The system also includes mounting means that limit longitudinal and lateral motion between the shafts.
A disadvantage of the systems described above is that the damper is typically mounted to the shaft after the driveline has been balanced, thus throwing off the balancing.
Yet another known system is disclosed in U.S. Pat. No. 6,312,340 B1 (Gassen et al.) Gassen et al. teach an integrated vibration absorber that is mounted within a hollow drive shaft.
Some disadvantages of all of these systems are that: 1) they contribute to an overall increase in the weight of the vehicle, thus resulting in less efficient fuel consumption; 2) they present additional difficulty in balancing the driveline; and 3) they require additional assembly.